Generally, electrical apparatuses operate with electric power supplied from a power supply. In receiving electric power from a power supply, usually, the electric power is supplied from the power supply to an electrical apparatus via a connector. The connector used in this case establishes electrical connection by mating a plug connector and a jack connector as disclosed in Japanese Laid-Open Patent Application No. 5-82208 and Japanese Laid-Open Patent Application No. 2003-31301.
On the other hand, in recent years, studies have been made, as a measure against global warming, of supplying direct-current, high-voltage electric power in power transmission in local areas as well. Such a form of power supply, which is reduced in power loss in voltage conversion or power transmission and does not require an increase in cable thickness, is considered desirable particularly for electrical apparatuses such as servers, which consume a large amount of electric power.
The electric power supplied to electrical apparatuses may affect a human body or operations of electronic components if the voltage of the electric power is high. In the case of using such high-voltage electric power for information apparatuses such as servers, connectors, where electrical connection is established, need to be different from those used for usual alternating-current commercial power supplies because the installation and the maintenance of the apparatuses are manually performed.